The present invention relates to a bearing seal for a water pump that is suitable for an application such as a water-cooled engine of an automobile and, in particular, to a bearing seal that prevents the intrusion of water, water steam, or the like into a bearing that supports a rotary shaft of a water pump, and which simultaneously prevents any leakage of grease from within the bearing to the outside.
As shown in FIG. 6, a water pump 30 that pressurizes cooling water housed in a pump chamber 50 of an engine to cause it to circulate is generally configured in such a manner that a rotary shaft 12, on which an impeller 32 is fixed at one end and a drive means 60 comprising a pully 61 and a drive belt 62 are fixed at the another end, is supported within a casing 38 by a plurality set of roller bearings 10 disposed having a distance therebetween in the axial direction. The cooling water is sealed from the exterior by a mechanical seal 40 that is disposed between the impeller 32 and the rolling bearings 10. However, since the sliding surface between the inner surface of the mechanical seal 40 and the rotary shaft 12 is in a water-lubricated state, water steam or the like will leak therefrom and will enter the roller bearings 10 side from the sliding surface if no further contrivance is provided. If steam or the like enters the interior of the roller bearings 10, it will damage the roller bearings 10. To prevent the intrusion of water steam or the like from the impeller 32 side into the roller bearings 10 in such a configuration, an annular seal body (not shown) is provided on the impeller 32 side of the roller bearings 10. Nitrile rubber, which has an excellent water resistance, or a fluororubber, which has an excellent thermal resistance, is used as the material of this annular seal body.